Using a 3 needle bind off to attach a sleeve

Like I've said, I think this is a nice way to attach arms, esp. if you're working with cotton or a cotton blend that seems prone to pulling or sagging and so not looking nice on your finished product.

• First, don't bind off your sleeves, even for the shaping at the edges.  Do this more like short rows, or as you "finish" with the stitches you're supposed to bind off, just place them on a holder of some kind (scrap yarn, safety pins, etc.).  When your sleeve is done, place all stitches back on the needle.
• Next, pick up the stitches along the body where you want to attach the sleeve.  
• One helpful tip is to NOT use the very last stitches, skip over those and pick up outer edge of the second edgemost stitich (I've marked it here with the head of the crochet hook).  This will give you a more stable and much nicer looking seam. You can see this in the second picture where I'm binding the two edges together and you can see the edgemost stitches make a selvage. 
• Second helpful tip is to pick up one half at a time, join that and then pick up the other half - that is start from the should seam and pick up down to the armpit.  Doing this will make it easier to pick up the right number of stitches at the best (most even) ratio.  Obviously, using circular needles for this works best. When I pick up for a perpendicular join I find that picking up 3 of every 4 rows usually gets me within a stitch or two of the right number and keeps the distribution of stitches from one piece to rows of the other piece correct.  You can see this in the third picture.
• Next you hold the two pieces of work right sides facing and just knit them off together - a 3 needle bind off.  I use a crochet hook to do this. See the second picture again for an action shot.

The final picture is of the finished joined seam.
I'll take some more pictures of the finished piece and post them tonight.